St. Louis Blues captain David Backes is injured on a hit by the Ottawa Senators' Colin Greening on Monday. / Bruce Bennett, Getty Images

by Kevin Allen, USA TODAY Sports

by Kevin Allen, USA TODAY Sports

U.S. Olympic hockey officials are probably as concerned about David Backes' injury as the St. Louis Blues are today.

Backes left Monday's game looking wobbly after taking a hit from the Ottawa Senators' Colin Greening. The Blues center is listed with an upper-body injury, making him the sixth potential U.S. Olympian out with an injury.

"At this point, the only injuries that are worrisome would be an injury with a diagnosis either unknown from a timeline standpoint or an injury return date very close to the Olympics," USA Hockey's Jim Johannson said. "It's probably a moving target, but any player not back by Feb. 1 is an obvious concern."

All six injured Americans are expected back by then. What we know about them:

Goaltender Jonathan Quick (Los Angeles Kings): Quick (groin muscle) is expected to be playing after Christmas, in plenty of time to be ready for the USA's first game Feb. 13 against Slovakia. He did light work on the ice with coaches Tuesday. Quick and Ryan Miller (Buffalo Sabres) are the USA's top two goaltending contenders.

Goaltender Jimmy Howard (Detroit Red Wings): A knee injury will sideline him for two to four weeks. He probably won't play again until after the team is named Jan. 1. He was considered a preseason favorite to be among the USA's three goalies. The problem: He wasn't playing well when he was injured. General manager David Poile must decide if the goalie's body of work and international experience still place him ahead of fellow contenders Cory Schneider (New Jersey Devils) and Ben Bishop (Tampa Bay Lightning). Bishop has played well but lacks big-game experience. Schneider doesn't have the same level of experience as Howard.

Right wing Ryan Callahan (New York Rangers): He is expected to recover from his knee injury in a couple of weeks. Because of his feistiness and skill, he is a lock to make the team.

Defenseman Brooks Orpik (Pittsburgh Penguins): Although concussions are tricky to predict, Orpik is skating again and expected back in time.

Defenseman Paul Martin (Pittsburgh): He is expected out until January with a broken leg but the Americans seem confident he'll be operating under full power by the Olympics.

Backes: The Americans will have to monitor this carefully, because center is an area of concern. The USA has six centers (Backes, Ryan Kesler, Joe Pavelski, Paul Stastny, Derek Stepan and Brandon Dubinsky) playing elite-level minutes. Those players are all playing 18 to 22 minutes a game.

The Americans need Backes because he offers a physical presence and scoring touch and is a leader.

Who's hot: Winger Blake Wheeler (Winnipeg Jets). With six goals in his past seven games, Wheeler is peaking peeking at the right time. His speed and reach are appealing, particularly because the Olympics will be played on the wider European ice surface.

Who's not: Defenseman Dustin Byfuglien (Winnipeg). He has 24 points but is minus 13 on a team that boasts some plus defensemen. No other Winnipeg player has a plus-minus worse than minus 6. Byfuglien is minus 8 in his past nine games.

Foreign market: The Finns have the most men's hockey medals (three) since the NHL began sending players to the Olympics in 1998. They could be a sneaky-good underdog in Sochi. The Finns traditionally have exceptional goaltending, and that will be true again with Tuukka Rask (Boston Bruins), Antti Niemi (San Jose Sharks) and Kari Lehtonen (Dallas Stars). They would be even stronger if Pekka Rinne (Nashville Predators) were healthy.

The Finns don't have the same level of depth on defense, where they have four current NHL players - Sami Salo (Tampa Bay) and Kimmo Timonen (Philadelphia Flyers), Olli Maatta (Pittsburgh) and Sami Vatanen (Anaheim Ducks).